Connector for electrical transmission lines



y 1957 J. R. BIRD 2,793,352

CONNECTQR FOR ELECTRICAL TRANSMISSION LINES Original Filed Aug. 21, 1946I I 39 27 44 5!, I 49 N 36 9 25 4 INVHVTOR JAMES RAYMOND BIRD ATTORNEYSUnited States Patent 2,793,352 CONNECTOR FOR ELECTlgICAL TRANSMISSIONLINE James Raymond Bird, Chagrin Falls, Ohio, assignor to BirdElectronic Corporation, Cleveland, Ohio, at corporation of Ohio Originalapplication August 21, 1946, Serial No. 692,116. Divided and thisapplication March 8, 1951, Serial No. 214,523

Claims. (Cl. 339-177) This invention relates to high frequencyelectrical devices and more particularly to an improved connector forjoining conductors, lines and other components of high frequencycircuits.

In the transmission of high frequency energy as by means of a coaxialline, it is important that all portions of the line conform to certainprinciples or laws, now well known, pertaining to diameter ratios of theinner and outer conductors, dielectric constants of the medium disposedin the spaces between the conductors, and avoidance of obstructions andsurface irregularities on the conductors. Practical considerationsrequire that components of high frequency systems be joined bydisconnectable couplings which permit removal and insertion of elementsat will for test, repair and replacement. Such couplings or connectorsmust embody the design principles referred to in order thatobjectionable reflections and other effects will be avoided.

It is, therefore, one of the principal objects of the present inventionto provide a high frequency connector structure that maintains thecharacteristic impedance of the lines connected thereby and that issubstantially free from objectionable reflections.

Another object is to provide a connector of the character mentionedwhich incorporates means for effecting circumferential line contactbetween the conductors joined substantially at the effective diameter ofsuch conductors. More specifically, the invention contemplates anarrangement wherein circumferential line contacts each substantiallycompletely circular in extent are established by the connectorcomponents at the outside diameter of the inner conductor of a coaxialline and at the inside diameter of the outer conductor of such line.

Another object is concerned with the provision of a non-polar connectorstructure for tubular lines, the connector components being alike oneach line end so that such line ends may be joined indiscriminately.

1 further object is to provide a connector composed of a minimum numberand kind of parts and that can be quickly and easily assembled anddisassembled without special training or instructions.

A suitable connector arrangement for tubular conduits may take the formof thin flange means on one, though preferably both of the conduits, incombination with a pilot element engageable with the thin flange meansto guide the flange means into proper position during drawing togetherof the conduits. The flange means may take the form of a thin shellwhich, in the case of a circular sectional conduit, is in the nature ofa ring of cylindrical shape, or substantially so. Likewise with acircular conduit, the guide or pilot may take the form of a ring whichembraces the shell flange and makes con tact therewith aroundsubstantially the entire circumferential extent of the shell. By makingthe inside diameter of the shell the same as that of the tubular conduiton which it is formed or mounted, the shell end and the companion shellor conductor end against which the shell is abutted in assembly, makecircumferential line contact, substantially completely circular inextent at said inside diameter. In a coax connector, one of the centerconductor ends is formed or provided with a circumferentially extendingshell flange which terminates in a tapered or knife-like edge that makescircumferential line contact with an axially tapered plug end on theother center conductor. The knife edge, in the case of a circularsectioned center conductor, has substantially the same diameter as theconductor so that the circular line contact has the same diameter as theconductor, or substantially so. The plug or the embracing shell flange,preferably the latter, is axially slotted so as to yield radially duringassembly, the slotted element being formed of suitable resilient metalthat has good electrical properties. When a solid dielectric is usedbetween the inner and outer conductors of the connector parts in acoaxial arrangement, the knife edged shell tube or flange is axiallyslotted so as to be compressed by the embracing solid dielectric andthereby held with the knife edge pressed firmly against the plug.Initial contact between the center conductor tube shell and the taperedplug occurs on the tapered portion of the plug at a diameter somewhatless than the center conductor diameter, the resilient fingers formed bythe slitting of the shell tube preferably being slightly pinchedtogether radially before assembly and deformed so tha the circle of theknife edge is slightly less in diameter than the center conductor. Theparts are so arranged that when the conductor is fully assembled, thecircular line contact of the knife edge is on the tapered portion of theplug at a diameter substantially equal to that of the inner conductor.

The principles of the invention as briefly outlined above areillustrated in a connector structure used to join one component of ahigh frequency electrical circuit to a coaxial line. Other applicationsof the invention are intended and will be apparent. The particularcircuit component illustrated is a termination including a tapered hornembracing a cylindrical resistance, as disclosed in my copending jointapplication for United States patent Serial No. 692,116, filed August21, 1946, now Patent 2,552,707 dated May 15, 1951, of which the presentapplication is a division. Reference is also made to United StatesPatent 2,663,753 dated December 22, 3, entitled Coupling Means forCoaxial Electrical Lines, which describes and claims similar subjectmatter, such patent having been issued on a copending application.

The device of the present invention provides connecting means ofseparable parts between the conductors of a high frequency coaxial lineand, by way of example, the members or parts of the line terminationstructure of the application referred to. Objects and advantages inaddition to those outlined above will become apparent from the followingdetailed description of a suitable embodiment of the invention made inconnection with the accompanying drawings forming a part of thespecification.

In the drawings:

Figure 1 is an elevational view partly in section and with parts brokenaway, showing a line terminator or dummy antenna attached to a coaxialtransmission line;

Fig. 2 is a section taken substantially on the line 2-2 of Fig. 1 andenlarged with respect thereto;

Fig. 3 is a sectional detail showing the structure of the connectordevice between the line termination and the coaxial transmission line;and

' Fig. 4 is a fragmentary expanded elevational View partly in section,with parts broken away and with parts removed, showing the interfittingarrangement for mounting the connector shells in the ends of the tubularouter conductors and the guide ring that embraces the meet ing ends ofthe shell connectors, this view being enlarged with respect to the otherfigures.

Referring to the drawings'by numerals of reference which indicate likeparts throughout the several views, the illustrative embodiment of thepresent invention is shown as a connector between a coaxial transmissionline of conventional character and the termination of .the applicationreferred to. The termination includes a hollow cylindrical resistor.member indicated generally by the numeral 1, enclosed in or surroundedby' a tapered metal housing or shell 2. The housing, of circular crosssection throughout its length, is concentric to the resistor 1 and is oftrumpet or horn shape.

The small diameter end of 'the'housing may be formed with a relativelyshort cylindrical portion or throat 3 whichembraces one end of theresistorl. A circular split clamping band 4 embraces cylindrical portion3 of the housing adjacent the juncture of the housing and the innerresistor member. Longitudinal slots.5 inthe' cylindricalportion 3 .ofthe housing, which permit limited expansion and contraction of thehousing to accommodate slight variations in diameter of the resistor l,facilitate assembly in production.

An inner connector member 14 is formed at one end with a tubularcylindrical element 15 which is telescopically received over the reduceddiameter end portion of the resistor l. The tubular element 15 has arelatively tight sliding fit over the end of the resistor so as to makeelectrical connection therewith and the parts may be soldered together.The diameter of the smooth outer surface of the tubular connectorelement 15 is substantially equal to that of the carbon film or otherresistive coating on the resistor, thus effecting an electricalconnection while maintaining substantially constant diameter, it beingunderstood that in soldering the tubular element onto the reduceddiameter end portion of the resistor any cracks and crevices between theend of the tubular element and the shoulder are filled.

The inner connector 14 may be formed of copper, brass or similar metalof high conductivity and has a tapered central body portion with anoutwardly directed smooth conical face. At the end of the connectoropposite the tubular element 15 is a cylindrical conductor element 17 ofless diameter than the tubular connector 15. The connector member 14 maybe formed in one piece by casting or by turning from bar stock, thecylindrical tubular end portion 15 and the conductor element 17 beinginte gral with the tapered bodyportion.

The large diameter end of the housing or horn 2 is telescopicallyreceived within a conductive cylindrical shell 13 which may be in theform of a brass or copper tube of uniform circular cross section. Atapered wedge sleeve 19 embraces the large diameter end of the horncasing 2 and is received in the angle between the horn and thecylindrical sleeve 18 to guide the latter in longitudinal or axialsliding movement over the horn and to maintain the parts in correctalignment.

Disposed about the connector member 14 in concentric relation theretoand telescopically received in one end of the conductive shell 13 forsliding engagement therewith is an outer connector member 2t This outerconnector 26 is formed with an internally tapered conical end element orportion 21 which is disposed concentrically about the tapered body ofthe inner connector 14 in confronting relation to the conical face 16 ofthe inner connector.

A solid dielectric tube 2.7 fills the annular space between thecylindrical element 17 of the inner connector member and the confrontingcylindrical face'of'the outer connector member. This tubular dielectricmay be polyethylene or such other compound having known dielectricproperties as is customarily employed in making solid dielectric coaxialcables.

In the transition zone of the connector assembly, that is, in the regionof the conical faces of the connector members the solid dielectric tube27 progressively changes or is reduced and tapered in cross sectionalarea. The dielectric material has its maximum cross section in the :3.region of the cylindrical conductor elements 17 and 20.

In the assembly of the line structure the born or casing 2 is placedover the resistor 1 and positioned so that the line of connectionbetween the carbon film and a conductive band painted on the carboncoating of the resistor at one end lies substantially in the plane ofthe large diameter circular end edge of the casing 2. The resistor 1 andthe horn or casing are retained in this adjusted position by tighteningscrew 31, which locks the clamping ring 4 about the small diameter endof the horn, holding the latter tightly about the end of the resistor 1and making positive electrical contact between the internal surface ofthe born or casing and a band of conductive metal paint on the other endof the resistor.

The tubular dielectric 27 and the outer connector member 2a areassembled over the inner connector member 14 and adjusted so that theends of the several conical or tapered surfaces are disposed in a commonplane. The sleeve 18 is placed over the horn or casing 2 and the wedgingsleeve 19 adjusted to align the parts. A clamping band 52, fitted withtightening screw 34, is applied about the shell 18 to hold the latter intight embracing relation about the connector member 20. Subsequently,the parts are soldered or brazed together.

The dummy antenna or line terminator is assembled to a coaxial highfrequency line comprising outer conductor 36 and inner conductor 37. Thecylindrical face 25 of the outer connector member 20 and the cylindricalelement 17 of the center conductor are designed with internal andexternal diameters respectively equal to corresponding diameters of thecoaxial line elements 36 and 37. Between the conductors 36 and 37 of theline is a solid dielectric tube 38 which is preferably of the samematerial as the solid dielectric tube 27.

The end of the inner conductor element 17 is formed into a thinsectioned circular shell portion 39 which receives a tapered or conicalplug portion 40 formed on the extreme end of the conductor 37 of thecoaxial line. The shell portion 39 is of the same outer diameter as theconductor 17. A number of axial slots 41 opening through the end of theshell portion 39 provide laterally flexible fingers 4-2 arranged in acylinder for simultaneous yielding contact with the tapered plug portion41) substantially at the maximum diameter of the latter which is thediameter of the inner conductor of the coaxial line. Electricalconnection is thus established between the circular knife edge and thetapered plug end substantially at a circular line contact locatedintermediate the axial limits of the tapered portion 4d of the conductor37 but substantially at the outer diameter of such conductor. The end ofone of the center conductors is resilient and deformable to provide forexpansion and contraction thereof so that the line contact between theconductors travels along the tapered and 4% as such tapered conductorplug end moves into and out of the socket of the conductor 17 inassembling and adjusting the structure.

The solid dielectric 27 in the connector assembly compressively abutsthe ends of the dielectric 38 of the coaxial line and the line ofabutment, indicated at 43, is disposed substantially in the plane of theends of the flexible fingers 422. The tapered plug portion as on the endof the inner conductor of the coaxial line extends beyond the end of thesaid dielectric tube 38.

In assembling the line termination with the coaxial line, the ends ofthe flexible fingers 42, formed with knife or tapered edges, make linecontact with the inner conductor 37 approximately at the base end of thetapered plug portion 46 thereof and substantially at the diameter of theconductor. Thus the connection provides substantially continuousconductor of uniform diameter and the transition between the innerconductors 17 and 37 is effected smoothly at a substantially circularline contact and without abrupt diameter change.

The ends of the solid dielectric tubes 27 and 38 project axially beyondthe outer connector member 20 and the outer line conductor 36,respectively, so that confronting end faces 45 and 46 of the outerconductors are disposed in spaced, confronting relation when the soliddielectric tubes are in abutment. At the ends of the outer conductors 2dand 36, thin contact shell elements 47 and 48 of metal such as brass,silver or copper, are received in embracing relation about andsubstantially flush with the ends of the dielectric tubes 27 and 38respectively. These shells are fitted into shallow recesses formed inthe interior faces of the outer conductors and abut circumferentialshoulders interiorly of the conductors. The internal diameter of theshells is approximately equal to that of the conductors so as to providesmooth continuous internal conductive surfaces.

In assembling the ine elements the shells 47 and 48 are brought intoend-to-end abutting relation to effect a positive electrical connectionbetween the outer conductors of the structure, such connection beingsubstantially continuous throughout the entire circumferential extent ofthe shells and being made along a line having a diameter approximatelythat of the internal faces 25 and 44 of the outer conductors. To insurethe making of the electrical connection at the diameter of the outerconductors, the meeting end edges of the shells 47 and 48 are beveled at51 about their outer end edges.

A guide ring 49 embraces the portions of the shells 47 and 48 which aredisposed in the space between the confronting faces 45 and 46 of theouter conductors. The ring 49 is of less width than the space separatingthe confronting faces 45 and 46 of the outer line conductors so as toprovide clearances which permit positive abutment of the contact shells.This guide ring is freely slidable on the shells and besides guidingthem into contact it serves as a reinforcement to resist collapse of theshells under mial compression.

External threads 5d are formed adjacent the ends of the outer conductors2t) and 36 so that a threaded coupling sleeve 52 may be employed tosecure the conductors together. The coupling sleeve 52 is threaded atone end over less than half its axial length and at its other end isformed with a circumferentially extending inwardly directed radialflange 54 which is engageable behind a circumferential shoulder 53 atthe end of the threaded portion of one of the outer conductors.

This coupling arrangement, wherein each outer conductor has a threadedend portion terminating at an inwardly directed radial shoulder,provides for interchangeable connectors in coaxial lines. Each threadedline end has a shoulder corresponding to the shoulder 53 and is fittedwith a threaded coupling sleeve corresponding to the sleeve 52. Inassembling coaxial lines so constructed, the coupling sleeve for eitherof the line ends may be employed to secure the parts together, theunused sleeve remaining idle and not being shown in the drawings.

During assembly, the parts are initially guided into correct relativeposition by the interfitting relation of the tapered plug end 4t)received in the socket provided by the fingered shell portion 39 of theinner conductor 17. As the parts are moved into final position, theguide ring 49, cooperating with the beveled ends 51 of the contactshells 47 and 43, guides the latter into abutting relation. Tighteningof the coupling sleeve 52 draws the parts firmly together, compressingthe abutting end faces of the dielectric tubes 27 and 3%, the dielectricbeing confined between the contact shells 47 and 48 and the innerconducting means. The incompressible character of the solid dielectricmaterial acts to force the flexible fingers 42 of the inner conductor 17tightly against and into positive electrical conducting relation to theinner conductor 37 of the coaxial line.

The principles of the present invention may be utilized in various ways,numerous modifications and alterations being contemplated, substitutionof parts and changes in 6 construction being resorted to as desired, itbeing understood that the embodiment shown in the drawings and describedabove is given merely for purposes of explanation and illustrationwithout intending to limit the scope of the claims to the specificdetails disclosed.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. In a coaxial line coupling structure or the like, a pair ofsubstantially rigid tubular conductors disposable in end to end relationand having externally threaded end portions, internally threaded sleevemeans embracing the threaded portions of the conductors for relativerotation, the sleeve means being arranged upon such relative rotation todraw the conductors together, axially directed substantially cylindricalrelatively thin shell flanges being in edgewise abutment with oneanother and on the ends of the conductors, said shell flanges havingsubstantially cylindrical outwardly directed guide surfaces of lessdiameter than the root diameter of the threads on the respectiveconductors having such guide surfaces, and guide ring means receivedembracingly about the guide surfaces of the shell flanges, said ringmeans having a substantially cylindrical inwardly directed face slidabletelescopically over the shell flange surfaces to pilot the conductorsinto aligned relation as the latter are drawn together.

2. In a coaxial line coupling structure or the like, a pair ofsubstantially rigid tubular conductors disposable in end to end relationand having externally threaded end portions, internally threaded sleevemeans embracing the threaded portions of the conductors for relativerotation, the sleeve means being arranged upon such relative rotation todraw the conductors together, axially directed substantially cylindricalrelatively thin shell flanges on the ends of the conductors, said shellflanges having substantially circular end faces disposed in confrontingrelation and substantially cylindrical outwardly directed guide surfacesof less diameter than the root diameter of the threads on the respectiveconductors having such guide surfaces, and guide ring means receivedembracingly about the guide surfaces of the shell flanges, said ringmeans having a substantially cylindrical inwardly directed face slidabletelescopically over the shell flange surfaces to pilot the conductorsinto aligned relation and the end faces into abutting relation as theconductors are drawn together.

3. In a coaxial line coupling structure or the like, a pair ofsubstantially rigid tubular conductors disposable in end to end relationand having externally threaded end portions, internally threaded sleevemeans embracing the threaded portions of the conductors for relativerotation, the sleeve means being arranged upon such relative rotation todraw the conductors together, axially directed substantially cylindricalrelatively thin shell flanges on the ends of the conductors, said shellflanges being in edge- Wise abutment with one another and havingsubstantially cyclindrical outwardly directed guide surfaces of lessdiameter than the root diameter of the threads on the respectiveconductors having such guide surfaces, guide ring means receivedembracingly about the guide surfaces of the shell flanges, said ringmeans having a substantially cylindrical inwardly directed face slidabletelescopically over the shell flange surfaces to pilot the conductorsinto aligned relation as the latter are drawn together, a pair of centerconductors, and solid dielectric bodies supporting the center conductorsco-axially in the tubular conductors, the dielectric bodies abutting oneanother substantially in the plane of abutment of the shell flanges.

4. In a coaxial line coupling structure or the like, a pair ofsubstantially rigid tubular conductors disposable in end to end relationand having externally threaded end portions, internally threaded sleevemeans embracing the threaded portions of the conductors for relativerotation, the sleeve means being arranged upon such relative rota tionto draw the conductors together, axially directed substantiallycylindrical relatively thin shell flanges on the ends of the conductors,said shell flanges having substantially circular end faces disposed inabutting relation and substantially cylindrical outwardly directed guidesurfaces of less diameter than the root diameter of the threads on therespective conductors having such guide surfaces, guide ring meansreceived embracingly about the guide surfaces of the shell flanges, saidring means having a substantially cylindrical inwardly directed faceslidable telescopically over the shell flange surfaces to pilot theconductors into aligned relation and the end faces into abuttingrelation as the conductors are drawn together, a pair of centerconductors, and solid dielectric bodies supporting the center conductorscoaxially in the tubular conductors, the end faces of the shell flangesbeing in abutment in a plane substantially normal to the axis alongwhich the conductors are drawn together and the dielectric bodies beingdisposed one in each tubular conductor and having substantially flatconfronting faces substantially abutting in the plane of abutment of thecircular end faces.

5. in a coupling assembly for a high frequency electrical linecomprising separable parts each having inner and outer coaxialconductors separated by solid dielectric material and means for holdingthe parts in assembled end to end relation, the combination of a taperedend portion on one of the conductors of one part, a plurality of fingerson the end of the corresponding conductor of the other part, the fingershaving extreme end edges positioned to yieldingly engage the saidtapered end portion substantially in a circular line contact surroundingthe latter upon drawing together of the parts in assembly, one side ofeach finger being disposed compressively against the dielectricmaterial, and thin cylindrical ring means carried by the otherconductors of the parts, said ring means. being arranged to be broughtinto aligned end to end abutting relation in assembly for establishingthe electrical connection therebetween, and said ring means also beingdisposed to embrace and confine the solid dielectric material in theannular space between the inner and outer conductors of the assembledcoupling.

6. In a high frequency electrical line coupling assembly of separableparts the combination of means for drawing and holding the partstogether in assembled relation, a relatively thin sectionedsubstantially cylindrical contact ring carried by one part and having acircular edge face disposed in cdgewise abutment with the other part inthe establishment of a circular contact in a plane normal to the axis ofthe assembly, the contact ring being positioned on the one part to bedrawn axially into said edgewise abutment during assembly, and meanshaving centering connection with the other part and disposed on theoutside of and embraced about the contact ring in sliding relation forholding the contact ring and the other part in axial alignment.

7. A high frequency electrical line coupling assembly comprisingseparable parts each having inner and outer coaxial conductors, meansfor drawing and holding the parts together in assembled relation, atapered plug end on one and a recessed socket on the other of the innerconductors, the plug end being received within the socket end to serveas primary centering means during initial assembly, ring contact meanscarried by the outer conductors and adapted to establish a substantiallycircular end to end abutment contact between the outer conductors of theparts, and means engaging the ring contact means for relative axialsliding. movement and adapted to guide the parts into said end to endabutment to serve as secondary centering means during final assembly.

8. In a coaxial line coupling structure or the like, tubular conductorsdisposed in end to'end relation and having spaced confronting end faces,at least one of the conductors having at its end a circumferentiallyextending axially directed shell of relatively thin sectioned conductivematerial, the shell being of greater length axially of the structurethan thickness radially and being generally of less radial thicknessthan either of the conductors, said shell and at least one of theconductors having inside surfaces of substantially the same curvatureradius, sleeve means embracing and having connection With the conductorsfor drawing the latter together end- Wise in assembly to compress theshell axially therebetween and to hold the conductors in said end to endrelation with the shell abutting the other shell or the end of aconductor, and guide ring means substantially surrounded by the sleevemeans and embracing the shell to reinforce the latter against collapse,the ring means being held against radial shifting relative to theconductors and disposed in the space between the confronting end facesof the conductors and having a substantially cylindrical inside surfaceslidable axially over and relative to the shell for guiding theconductors together in assembly.

9. In a coaxial line coupling structure or the like, a pair ofsubstantially rigid tubular conductors disposable in end to end relationand having externally threaded end portions, internally threaded sleevemeans embracing v the threaded portions of the conductors for relativerotation, the sleeve means being arranged upon such relative rotation todraw the conductors together, means on the ends of the conductorsproviding substantially cylindrical outwardly directed guide surfaces ofless diameter than the root diameter of the threads on the respectiveconductors having such guide surfaces, said guide surface means beingformed with radially narrow circular end faces contiguous to the surfacegenerated by the internal surfaces of the conductors and arranged to bebrought into axial abutment when the conductors are drawn together toestablish circular abutment contact between the conductors, and guidering means receivable embracingly about the guide surfaces of theconductors, said ring means having a substantially cylindrical inwardlydirected face slidable telescopically over the conductor guide surfacesto pilot the conductors into aligned relation as the circular end facesare drawn together into abutment.

10. In a coaxial line coupling structure or the like, a pair ofsubstantially rigid tubular conductors disposable in end to endrelation, said conductors being formed with internal cylindrical coaxialconductive surfaces and having externally threaded end portions,internally threaded sleeve means embracing the t readed portions of theconductors for relative rotation, the sleeve means being arranged uponsuch relative rotation to draw the conductors together, means on theends of the conductors providing substantially cylindrical outwardlydirected guide surfaces of less diameter than the root diameter of thethreads on the respective conductors having such guide surfaces, saidguide surface means on the conductors being formed with substantiallycircular end faces contiguous to the internal conductive surfaces of theconductors, the end faces being radially narrow and disposed in abutmentin a plane substantially normal to the axis of the cylinder defined bythe guide surfaces, and guide ring means receivable embracingly aboutthe guide surfaces of the conductors, said ring means having asubstantially cylindrical inwardly directed face slidable telescopicallyover the conductor guide surfaces as the conductors are drawn togetherto pilot the conductors into aligned relation and the end faces intoabutment.

References Cited in the file of this patent UNITED STATES PATENTS442,575 Eckert et al Dec. 9, 1890 839,224 Stokes Dec. 25, 1906 2,176,718,Linde Oct. 17, 1939 2,209,152 Daniels July 23, 1940 k (References onfollowing page) Bruno Dec. 22, 1942 Webber July 10, 1945 Webster Feb.17, 1948 Johannesen Sept. 14, 1948 Robinson Oct. 12, 1948 Collard Aug.15, 1950 10 Wilson Apr. 10, 1951 Bird et al. May 15, 1951 Waite Oct. 28,1952 Bird Dec. 22, 1953 FOREIGN PATENTS France Mar. 20, 1939

